(Remember, this review is based on my opinion)
(And there may or may not be spoilers! Read at your own risk!)
(For the sake of this review I will use OP as an abbreviation for "One Piece")
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I actually don't care for OP at all.

You probably wanna rip my throat out and question why I dislike one piece but just hear me out before you cause someone harm.
I'm here to present my opinion which might as well be activating one of three global thermonuclear bombs. So just sit right and read instensly.

OP is probably good here and there but for the most part, it seems like it's just boring. I try to go back to it every now and then but I just can't there's not much to this series in my eyes other than filler which is mostly bad in big anime like this.

I stopped watching OP back in 2009 and at that point was just bored of the anime itself, I wasn't interested in the characters, I was watching like every one out of 8 episodes due to the amount of filler or just overall boringness of the episodes.

At this point I've probably lit the fuses of the apocalypse as most of its community (that I've experienced) bring torrents of hate to people who dislike they're favorite show.
But let's get to other reasons why I hate OP.

I think the overall art style and design of the characters are boring. Unique, but boring.
Nothing in this anime seems very relateable and I can't become attached to it like I can other anime.

According to a friend of mine who still watches the anime or at least keeps tabs on it, there was a point where they found the 'one piece' but it was only 'one piece' of the treasure. I would just like to say. That's really stupid, and probably the lamest way to extend your anime.